The muffler for an internal combustion engine functions to suppress or modulate the noise emanating from the running engine. A problem with mufflers is that the reduction in noise frequently causes back pressure at the outlet of the engine. This back pressure causes a reduction in the efficiency of operation of the engine, causing lower fuel efficiency and lower power output.
The suppression of the engine exhaust noise has been approached by use of mufflers connected in fluid flow communication with a manifold with which the exhaust ports from the engine cylinders are connected. Exhaust gases and acoustic noise associated with the firing of a fuel in the engine cylinders are transmitted to the muffler. The muffler directs the exhaust gases through a housing having sharp turns, sharp edges, packing of various types, baffles, and perforated or non-perforated tubing are used to alter the flow of the gases and reduce the noise through the muffler in attempts to change the direction of flow of the gases and accompanying noise as they pass through the muffler, all with the intent to reduce the noise level exiting the muffler while minimizing the resistance to flow of the gases through the muffler, thereby minimizing the back pressure to the engine.